85mm primes on *ist DS

I'd appreciate any comments on experience with either the Jupiter 9 85/2 or SMC Takumar 85/1.8 (both M42 mount) on a digital body. Both I believe are well regarded on film cameras but I gather lens performance on digital can be different - something to do with coatings (or rather the lack of) on the rear element affecting reflections from the sensor? The jupiter 9 is supposed to have good bokeh.

Thanks,
Rowdy

Although a great deal is made of the coating issue, the pentax SMC coating is so good anyway that I would not worry too much.

The Jupiter 9 is a poor lens by comparison, and very variable in quality from sample to sample.

Personally, I would stick with any Pentax lens with a high degree of confidence.

Digital cameras need the light to hit the sensor from as close to perpindicular as possible. Any light that doesn't can cause chromatic abberations and it's for this reason that we see measures being taken now to address this with new lens designs, including measures internally to cut down reflections. Some lenses have internal baffles to cut down internal reflections and others have coatings were none would have been used before.

I've not used either of the lenses you mention, however my own 85mm lens (the FA*) was produced before the digital era and doesn't appear to suffer from chromatic aberattions - in fact the only lens I have which was specifically designed for digital (the 18-55 kit lens) suffers to a more noticeable degree (although it's not bad either).

The digital SLR only uses the centre portion of the field of view of a 35mm format lens, which helps a lot when using older lenses anyway.

telecentric design may well be the way forward, but there are many other factors.

I have tested about a dozen of primes on my ist*DS, and among them the K85/1.8. As for image quality the best will be the K30/2.8. Next come FA35/Al, FA50/1.4 and K85/1.8. The screw mount 85/1.8 and the K85/1.8 will be the same optical construction.
The K85/1.8 is very contrasty, has high resulution (indeed at f11) and good colours - a great performer.
All the primes have very little CA compared to zoomes (exept my M200/4). On pictures from the K85 i couldn´t find any traces from CA at all.

Thanks for all the info. It's reassuring to know the SMC 85/1.8 performs well on the *ist DS as I've just bought one. but haven't had a chance to do an in depth evaluation.

Rowdy

I have used both the jupiter 9 and the 85mm/1.8 (K.version). The jupiter 9 was not a top performer, but still a very good lens, but the pentax was better, so i stuck with the pentax.

Ludvik